+# [*user_domain*]
+# (Optional) Domain for $auth_name
+# Defaults to undef (use the keystone server default domain)
+#
+# [*project_domain*]
+# (Optional) Domain for $tenant (project)
+# Defaults to undef (use the keystone server default domain)
+#
+# [*default_domain*]
+# (Optional) Domain for $auth_name and $tenant (project)
+# If keystone_user_domain is not specified, use $keystone_default_domain
+# If keystone_project_domain is not specified, use $keystone_default_domain
+# Defaults to undef
+#